1. Technical Field
The present invention relates to a semiconductor device manufacturing technology, and more particularly, to a polishing composition for chemically-mechanically polishing a metal compound thin film, a method of preparing the polishing composition, and a chemical mechanical polishing method using the polishing composition.
2. Related Art
As demands for portable digital application devices such as a digital camera, an MP3 player, a personal digital assistant (PDA), and a mobile phone have recently increased, the nonvolatile memory market has grown rapidly. As flash memories which are programmable nonvolatile memory devices have reached their scaling limits, phase-change random-access memories (PcRAMs) or resistive random-access memories (ReRAMs) using a variable resistor whose resistance value may be reversely changed have attracted attention as alternative nonvolatile memory devices. Since the alternative nonvolatile memory devices may use physical characteristics of the variable resistor as data, cells may be simply configured and thus the alternative nonvolatile memory devices may be miniaturized.
Since a resistance value of a chalcogenide material such as a germanium (Ge)-antimony (Sb)-tellurium (Te) alloy is changed according to a phase change or a magnitude or a width of an electrical signal applied to the chalcogenide material, the chalcogenide material has been widely studied as a material for a nonvolatile memory device. In the nonvolatile memory device, the chalcogenide material is formed to have a damascene structure that fills holes formed in an interlayer insulating film in order to increase a degree of integration, a chemical mechanical polishing (CMP) method may be used as a planarization method using etchback.
However, since the chalcogenide material is a multi-component metal alloy including two or more metal elements, the chalcogenide material may encounter a problem which is different from a problem of copper or aluminum which is conventionally used for a wiring encounters during a CMP process. Also, when the chalcogenide material is formed to have a damascene structure, since the chalcogenide material may be formed to have a cell pitch equal to or less than 20 nm in order to have a high degree of integration, a surface to be polished is required to have a low surface roughness and a low defect density. However, since a colloidal silica slurry has a high surface roughness, it is difficult to increase a resolution of a lithography process.
Such requirements apply not only to a material for a phase-change memory device such as a chalcogenide material but also to a metal oxide material including two or more metal elements such as a perovskite-based metal compound such as PbZrxTi1-xO3.